The ability of histone deacetylase (HDAC) inhibitors (HDACis) to activate HIV transcription represents an exciting new approach to flush the virus out of latently infected CD4 T cell reservoirs for destruction by antiretroviral drugs and the host immune response. However, inhibiting HDAC activity is likely to have multiple off-target effects and these must be identified prior to using HDACis as a therapeutic option. Initially this project will identify the off target affects for three HDACis (MRK-2, -3 and vorinostat/MRK-5) with respect to the genes they modulate in primary resting CD4 T cells from humans and rhesus macaques (Aim 1a). Gene expression results will also be used to determine if HDACi treatment of human and rhesus CD4 T cells modulates similar subsets of genes and thus confirm that the rhesus macaque represents a good model system for evaluating the therapeutic value of HDACi treatment in humans. Next, HDACi modulated genes will be identified in primary activated human CD4 T cells to determine the difference in off-target effects compared to resting cells (Aim 1b). In relation to HIV therapy, it will be important to identify HDACi compounds that limit the induction of proapoptotic and antiproliferative responses following the activation of virus replication that may effect the ability of the human host to clear this pathogen. Once the off-target effects of HIV treatment have been delineated, it will be important to identify the mechanism by which these effects occur. The inhibition of HDACs is thought to alter the acetylation state of histones in regulatory regions, which in turn modulate gene expression. By coupling chromatin immunoprecipitation (ChIP) with a DMA promoter array (chip), we will use a ChIP-chip approach to identify promoters in the human genome that contain modified histones (Aim 2). Therefore, using the HDACi modulated genes identified in Aim 1, it will be possible to determine the extent to which histone modification correlates with gene expression. Finally, promoter, pathway and ontology analysis, as well as literature mining, will be used to identify the non-histone regulatory factors controlling the transcription of genes whose modulation did not correlate with histone modification (Aim 3). The acetylation state of non-histone regulatory factors will be assessed in Western blots and correlated with gene expression. When these studies are complete we will have assessed the utility of HDACi treatment for HIV therapy with respect to off target effects. HIV is able to persist within infected patients by hibernating in specific cells of the body. Compounds have been discovered which flush HIV out of hibernation so that it may be destroyed with antiviral drug therapy and by the body's own defenses. To investigate the usefulness of these compounds, this project will discern what other effects these compounds have with respect to turning genes on and off, and will determine the mechanism by which these effects occur.